Go to D:\Oracle\oraclexe\app\oracle\product\11.2.0\server and click over the file Get_Started and choose properties, there change the %HTTPPORT% for you port, usually 8080, will be like this: http://127.0.0.1:8080/apex/f?p=4950

I probably don't have an expert opinion on this, since I am very new to oracle DB, but here is what I noticed:

I also installed Oracle DB, and I also got the same error message. And I also couldn't open the home page. However...
I realized(after uninstalling and installing again) that I have actually intentionally stopped the Oracle Database after the first installation, through Task Manager(I noticed it drains a lot of RAM). So the error message should be ignored. What is important is to check if the DB is running.
Which is my explanation why I couldn't connect to the homepage, or connect to any user account. Because they weren't running :]

You can resolve this eeror by either creating a system variable for %HTTP_PORT% or just set it manually to 8080 in the properties of the file pointed at by the desktop shortcut. This should let you access the web-based localhost controls for your oracle instance on your machine:)